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Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open, and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e., berry mass, number of fruits, and fruit density [kg/ha], among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), North America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-2005 (21 studies), 2006-2010 (40), 2011-2015 (88), and 2016-2020 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA)., (© 2021 The Ecological Society of America.)

Landscape fragmentation and habitat loss at multiple scales directly affect species abundance, diversity, and productivity. There is a paucity of information about the effect of the landscape structure and diversity on honey bee colony strength in Africa. Here, we present new insights into the relationship between landscape metrics such as patch size, shape, connectivity, composition, and configuration and honey bee (Apis mellifera) colony strength characteristics. Remote-sensing-based landscape variables were linked to honey bee colony strength variables in a typical highly fragmented smallholder agroecological region in Kenya. We examined colonies in six sites with varying degrees of land degradation during the period from 2017 to 2018. Landscape structure was first mapped using medium resolution bitemporal Sentinel-1 and Sentinel-2 satellite imagery with an optimized random forest model. The influence of the surrounding landscape matrix was then constrained to two buffer distances, i.e., 1 km representing the local foraging scale and 2.5 km representing the wider foraging scale around each investigated apiary and for each of the six sites. The results of zero-inflated negative binomial regression with mixed effects showed that lower complexity of patch geometries represented by fractal dimension and reduced proportions of croplands were most influential at local foraging scales (1 km) from the apiary. In addition, higher proportions of woody vegetation and hedges resulted in higher colony strength at longer distances from the apiary (2.5 km). Honey bees in moderately degraded landscapes demonstrated the most consistently strong colonies throughout the study period. Efforts towards improving beekeeper livelihoods, through higher hive productivity, should target moderately degraded and heterogeneous landscapes, which provide forage from diverse land covers., (© 2021 by the Ecological Society of America.)

We assess the monetary value of forage provisioning services for honeybees as provided by an alien tree species in the Western Cape province of South Africa. Although Eucalyptus cladocalyx is not an officially declared invader, it is cleared on a regular basis along with other invasive Eucalyptus species such as Eucalyptus camaldulensis, and Eucalyptus conferruminata (which have been prioritised for eradication in South Africa). We present some of the trade-offs associated with the clearing of E. cladocalyx by means of a practical example that illustrates a situation where the benefits of the species to certain stakeholders could support the containment of the species in demarcated areas, while allowing clearing outside such areas. Given the absence of market prices for such forage provisioning services, the replacement cost is used to present the value of the loss in forage as provided by E. cladocalyx if the alien tree species is cleared along with invasive alien tree species. Two replacement scenarios formed the basis for our calculations. The first scenario was an artificial diet as replacement for the forage provisioning service, which yielded a direct cost estimate of US$7.5 m per year. The second was based on a Fynbos cultivation/restoration initiative aimed at substituting the forage provisioning service of E. cladocalyx, which yielded a direct cost of US$20.2 m per year. These figures provide estimates of the potential additional cost burden on the beekeeping industry if E. cladocalyx is completely eradicated from the Western Cape. The cost estimates should be balanced against the negative impacts of E. cladocalyx on ecosystem services in order to make an informed decision with regard to appropriate management strategies for this species. The findings therefore serve as useful inputs to balance trade-offs for alien species that are considered as beneficial to some, but harmful to other., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Value estimates of ecosystem goods and services are useful to justify the allocation of resources towards conservation, but inconclusive estimates risk unsustainable resource allocations. Here we present replacement costs as a more accurate value estimate of insect pollination as an ecosystem service, although this method could also be applied to other services. The importance of insect pollination to agriculture is unequivocal. However, whether this service is largely provided by wild pollinators (genuine ecosystem service) or managed pollinators (commercial service), and which of these requires immediate action amidst reports of pollinator decline, remains contested. If crop pollination is used to argue for biodiversity conservation, clear distinction should be made between values of managed- and wild pollination services. Current methods either under-estimate or over-estimate the pollination service value, and make use of criticised general insect and managed pollinator dependence factors. We apply the theoretical concept of ascribing a value to a service by calculating the cost to replace it, as a novel way of valuing wild and managed pollination services. Adjusted insect and managed pollinator dependence factors were used to estimate the cost of replacing insect- and managed pollination services for the Western Cape deciduous fruit industry of South Africa. Using pollen dusting and hand pollination as suitable replacements, we value pollination services significantly higher than current market prices for commercial pollination, although lower than traditional proportional estimates. The complexity associated with inclusive value estimation of pollination services required several defendable assumptions, but made estimates more inclusive than previous attempts. Consequently this study provides the basis for continued improvement in context specific pollination service value estimates.

Although several factors influence herbivore insect distributions at any particular scale, the most important determinants are likely to differ between species with different life histories. Identifying what these factors are and how they relate to life history forms an important component of understanding the population dynamics of species, and the habitat requirements necessary for their conservation. The pupal stage of two wild silk moth species, Gonometa postica Walker and G. rufobrunnea Aurivillius (Lepidoptera: Lasiocampidae), is the target of harvesting practices that are totally dependent on the availability of pupae from natural populations. Consequently, and partly due to poor knowledge of the species' biology, there is substantial interest in the distribution of pupae among and within trees for both these species. It was investigated whether between- and within-tree pupal distributions in these two species are non-random, and if so, whether there are relationships between pupation site use and tree characteristics such as tree size, available pupation space and branch position. Between-tree patterns in pupal abundance were random in terms of absolute spatial position, but markedly non-random with respect to tree characteristics. The apparent G. postica pupae were aggregated on large larval host plants, whereas the cryptic G. rufobrunnea pupae were aggregated on non-host plants. These patterns reflect the life history differences of the two species. In contrast, at the within-tree scale, branch position, aspect and tree shape influenced pupation site choice similarly for both species. These patterns might be related to microclimate. Documenting between-tree and within-tree patterns in Gonometa pupal distributions is the first step towards explaining pupation site selection, as well as identifying possible evolutionarily selective factors in the species, and generating testable hypotheses from these.

Density-dependent processes are fundamental in the understanding of species population dynamics. Whereas the benefits of considering the spatial dimension in population biology are widely acknowledged, the implications of doing so for the statistical detection of spatial density dependence have not been examined. The outcome of traditional tests may therefore differ from those that include ecologically relevant locational information on both the prey species and natural enemy. Here, we explicitly incorporate spatial information on individual counts when testing for density dependence between an insect herbivore and its parasitoids. The spatially explicit approach used identified significant density dependence more frequently and in different instances than traditional methods. The form of density dependence detected also differed between methods. These results demonstrate that the explicit consideration of patch location in density-dependence analyses is likely to significantly alter current understanding of the prevalence and form of spatial density dependence in natural populations.